AN IMC ACR ACFT APCHING ZGGG BEGAN AN EARLY DESCENT ON A LOC GS OTS APCH AND THE GPWS 'TERRAIN PULL-UP' ACTIVATED. AN ESCAPE MANEUVER WAS FOLLOWED BY A VISUAL APCH.

Narrative

ARR INTO ZGGG. INITIALLY CLRED THE ATA1Z ARR WITH THE EXCEPTION OF THE ILS GS OTS RWY 20L. FMC WAS LOADED ACCORDINGLY PRIOR TO DSCNT. APCHING ATOGA WE WERE GIVEN A NEW SID AND THE ATIS WAS INDICATING WHAT WE HEARD AS A QUESTIONABLE GS ON THE 20 RWYS AT ZGGG. THE NEW SID WAS THE ATA11A. AS SOON AS THE SID WAS LOADED WE WERE INSTRUCTED THAT WE WOULD FLY THE ILS APCH TO RWY 20R. IT WAS LOADED; BUT BASED ON THE PREVIOUS ATIS INFO WE AGREED WE WOULD FLY THE ILS GS OTS. PF AND PM REBRIEFED THE APCH FOR RWY 20R AND SET THE ILS GS OTS MINIMUMS OF 480 FT ON BARO. INSIDE ATAGA; WE DEALT WITH AT LEAST 2 WX DEVS AROUND BUILDUPS AND CONTINUED WITH A NORMAL DSCNT AND SLOWDOWN AND CONFIGN. WE WERE GIVEN ONE MORE RADIO FREQ CHANGE TO THE FINAL APCH CTLR. HE CLRED US TO INTERCEPT THE LOC AND TO DSND TO 900 METERS. AT 14 DME ON THE IPP LOC WE WERE FULLY CONFIGURED AND SLOWED AND THEN CLRED TO CONTACT TWR. ONCE TWR WAS CONTACTED; WE WERE CLRED THE ILS; BUT BASED ON PREVIOUS CREW DISCUSSIONS AND THE FACT THE GS APPEARED UNRELIABLE; THE APCH WAS CONTINUED AS A GS OUT AND MINIMUMS FOR RWY 20R REMAINED 480 FT. AT 12.3 DME AND LEVEL AT 900 METERS; THE PF STARTED A DSCNT IN FPA TO 480 FT WHICH HAD BEEN SET IN THE FCP ALT WINDOW. SHORTLY THEREAFTER WE GOT A GPWS 'TERRAIN; TERRAIN.' AS SOON AS WE GOT THE FIRST GPWS WARNING WE GOT A SUBSEQUENT GPWS 'TERRAIN PULL-UP.' I IMMEDIATELY FOCUSED ON THE TERRAIN DISPLAYED ON THE NAV DISPLAY AND SAW NO TERRAIN POP UP OR ANY OTHER TERRAIN INDICATED FOR OUR RTE OF FLT INBOUND. THE PF (FO) IMMEDIATELY EXECUTED A CFIT. THE CAPT STATED HE HAD VISUAL CONTACT WITH THE GND AND NOTED AN ALT OF 2000 FT IN THE RADAR ALTIMETER. THERE WAS NO FURTHER GPWS ALERT. THE PF AND THE PM BOTH DECLARED CLR OF CLOUDS AND TERRAIN AT 3300 FT MSL AND I SAW 7.8 DME ON IPP. WE CONTINUED THE APCH TO AN UNEVENTFUL LNDG. I BELIEVE THE MAJOR CONTRIBUTING FACTORS TO THIS INCIDENT ARE AS FOLLOWS: 1) COMS. THE CTLR CLRED US TO 900 METERS. I THINK HE EXPECTED US TO FLY THE ILS AND INTERCEPT IT AT 900 METERS. WE BELIEVED; BASED ON ATIS WE HAD TO FLY A GS OTS BECAUSE THE GS WAS OUT. IT APPEARED LATER IN THE APCH VERY ERRATIC; WHICH REINFORCED OUR BELIEF WE WERE FLYING THE CORRECT APCH. HE WAS VERY HARD TO UNDERSTAND AND I MADE THE DECISION NOT TO ASK THE PF/PM TO RECONFIRM THE APCH CLRED BECAUSE IT SEEMED THE CTLR WOULD GET CONFUSED WITH WHAT WE WERE REQUESTING. 2) COMMERCIAL CHART IS ALTS. THE FAF ALT ONLY SHOWS FEET; YET WE FLY IT IN METERS. IN THE HEAT OF THE BATTLE; IT WOULD BE NICE TO HAVE THE METERS PRINTED THERE. 3) POSSIBLE MAP SHIFT. WE WERE ON THE LOC AT 9 DME AT 2800 FT WHEN WE GOT THE GPWS. NOTHING APPEARED ON THE NAV DISPLAY AS FAR AS ANY TERRAIN INDICATION AT OUR IMMEDIATE LOCATION OR ANYWHERE ELSE IN OUR FLT PATH ON THE APCH. 4) WORKLOAD. LOTS HAPPENING REAL FAST. ADD IN THERE FEET TO METERS AND LANGUAGE BARRIERS WITH APCH AND THINGS GOT COMPLICATED FAST.